Non-linear transducer armature



Oct. 24, 1961 E. D. SIMSHAUSER NON-LINEAR TRANSDUCER ARMATURE Filed May 6, 1960 TS m QAU S NAV WM R M l O M D T G A M w E Un ted a es P tent 3,005,880 f NON-LINEAR TRANSDUCER ARMATURE Elvin D. Simshauser, Merchantville, N.J., assignor to the United States of America as represented by the Secretary of the Air Force Filed May 6, 1960, Ser. No. 27,463

' Claims. (Cl. 179-1 14) v This invention relates to sound-powered telephones, and more 'particularly'to a telephonic transducer adapted to act either as a transmitter to generate electrical oscillations in response "to'acou'stica'l energy, or as a receiver to translate electrical oscillations into acoustical vibrations.

In reed armature type acoustic transducers, an effective way of increasing the sensitivity is to increase the magnetic flux density in the air gaps. This procedure has heretofore thought to be limited by instability due to the increase in the non-linear magnetic forces.

It is an object of the invention to provide a transducer having improved efficiency and better intelligibility over similar devices heretofore known.

It is a further object of the invention to provide a more sensitive transducer which has an increased magnetic flux density in the air gaps and a means for producing a nonlinear mechanical stiifness to oppose the non-linear magnetic forces created by the increased magnetic flux density.

More particularly, it is an object of the invention to provide a more sensitive reed armature type acoustic transducer which has an increased magnetic flux density in the air gaps and a curved surface for the armature to bend against to oppose the non-linear magnetic forces created by the increased magnetic flux density.

According to the invention, an armature is clamped between two spacer blocks which are rigidly fastened to the pole pieces. The spacer block surfaces which contact the armature are curved so that as the armature bends away from center, its unsupported length decreases and stiffness increases. It is possible to obtain a forcedis-placement function, by using the proper shape, which is the exact opposite of the non-linear magnetic force displacement function involved.

Other objects, novel features and advantages of this invention will become apparent on consideration of the embodiment illustrated in the accompanying drawings and hereinafter described.

In the drawing:

FIG. 1 is a view partly in section showing unit formed in accordance with certain features of the invention; and

FIG. 2. is a bottom view of the unit illustrated in FIG. 1 minus the speaker portion of the unit.

Referring more particularly to the drawing, wherein similar reference numerals designate corresponding parts throughout, there is shown in FIG. 1 an acoustic diaphragm 1 clamped at its marginal portion between a pair of clamping rings 3 and covered with a cover plate 5 having one or more openings 7 therein. Connected to the diaphragm 1 at one of its ends is a drive rod 9 which has its other end connected to a reed armature 1'1 of the cantilever type. The armature is secured by clamp screw 12 and spacer blocks 19 and extends through air gap 15 between the pole pieces 13. A permanent magnet 17 supplies fiux to the air gap 15. The drive rod 9 has an axis of motion and is movable freely along that aXlS.

The armature 11 is E-shaped and the central extension of the armature, as shown by FIG. 2, is clamped between the spacer blocks 19. The spacer blocks 19 are silver soldered or otherwise rigidly fastened to the pole pieces 13. The surfaces 21 of the spacer blocks which contact the armature are curved so that as the armature bends away from center, its unsupported length decreases and stiifness increases. The exact shape of the curved surfaces 21 is dependent upon the non-linear magnetic force displacement function involved. The proper shape must be such that a force displacement function is ob- I tained that is the exact opposite of the non-linear magnetic force displacement'function. v

i From the foregoing description, it will be apparent to those skilled in the art that the output from t-he transducer described in theinvention would be greater than that obtained from the presently used sound-power transducers. The improved efficiency could result in a saving in size and weight and could provide a sound-powered transducer that is more convenient to use with better intelligibility.

Although but a single embodiment of the invention has been shown and described, it will be apparent to those skilled in the art that many other forms thereof, as well as changes in that described, are possible.

I claim:

1. An electromechanical transducer for a sound-powered telephone device comprising a magnet, a pair of pole pieces secured to and directed inwardly from the ends of said magnet, a pair of curved elongated spacer blocks secured to said pole pieces, and a reed armature clamped between said spacer blocks at the end farthest from said pole pieces and extending unsupported therefrom between the remaining portion of the said curved spacer blocks and said pole pieces, so that as the said armature bends away from center its unsupported length between the said spacer blocks decreases and stifiness increases.

2. An electromechanical transducer for a sound-powered telephone device com-prising a permanent magnet for producing flux, a pair of pole pieces secured to and directed inwardly from the end of said magnet to form an air gap, a pair of elongated spacer blocks, means for fastening the said spacer blocks to the said inwardly directed portion of the pole pieces, and an E-shaped reed armature clamped between said spacer blocks at the end farthest from said pole pieces and extending unsupported therefrom between the remaining portion of the said spacer blocks and through said air gap, the portion of the said spacer blocks whereat the said armature is unsupported being curved so that as the armature bends away from center its unsupported length decreases and stiffness increases.

3. A sound-powered telephone device comprising: a vibratile member; an electromechanical unit including a magnet, a pair of pole pieces secured to and directed inwardly from the ends of said magnet, a pair of curved elongated spacer blocks secured to said pole pieces, and a movable member clamped between said spacer blocks at the end farthest from said pole pieces and extending therefrom unsupported between said curved spacer blocks and said pole pieces so that as the said movable member bends away from center its unsupported length between said spacer blocks decreases and stiffness increases; and means coupling said movable member to said vibratile member.

4. A sound-powered telephone device comprising: a vibratile member; an electromechanical unit including a magnet, a pair of pole pieces secured to and directed inwardly from the ends of said magnet to form an air gap, a pair of elongated spacer blocks, means for fastening the said spacer blocks to the said inwardly directed portion of the pole pieces, and an armature clamped between said spacer blocks at the end farthest from said pole pieces and extending unsupported therefrom between said spacer blocks and through said air gap, the portion of the said spacer blocks whereat the said armature is unsupported being curved so that as the armature 3 bends away from center its unsupported length decreases and stiflinessincreases; and means coupling said armature to said vibrati-le member.

5. A sound-powered telephone device comprisingp a Vibratile member; an electromechanical unit including a permanentmagnet, a pair of pole pieces secured to and directed inwardly from the ends of said magnet to form an air gap, a pair of elongated spacer blocks, means for fastening the said spacer blocks to the said inwardly directed portion -of the pole pieces, and an E-shaped reed armature slightly longer in length than said spacer blocks clamped between said spacer blocks at the end farthest frornsaid pole pieces and extendingunsupported therefrom between the remaining portion of the said spacer blocks and through said air gap, the portion of 15 1,052,453

4 said spacer blocks whereat the said armature is unsupported being curved from the end farthest from the pole pieces so that as the armature bends away from center its unsupported length decreases and stiffness increases; and mean coupling said armature to said vibratile member.

References Cited in the file of'this patent UNITED STATES PATENTS 10 2,343,859 Baldwin 14, 1944 FORElGN PATENTS 218,774 Switierland Dec. 31, 1941 a 396,165 Great Britain' Aug. 31933 Germany V V Mar. 12, 1959 

